1. Field of the Invention
This invention relates generally to a burn-in socket for removably loading an IC package having a plurality of solder balls in order to make an electrical connection with contacts of the socket, and more particularly, to a burn-in socket having a loading plate adapt for a type of IC package which has protrusions at the bottom thereof, and else adapt for at least two type of IC packages of different configurations.
2. Description of the Related Art
IC packages are usually subjected to pass a so-called burn-in test, in which the IC packages are placed in an oven and operated for a time at an elevated temperature, and under a voltage source that is greater than the rated value. Those IC packages that continue to perform satisfactorily are then approved for shipment.
An IC package generally defines a top surface and a bottom surface. A plurality of conducting leads, for example solder balls, are attached to the bottom surface for electrical contact with the terminals of a burn-in socket. One type of the IC package for example is called DDR package (DDR hereinafter), which is widely used in memory storage. Parts of the types of the conventional DDRs are equipped with some protrusions or ribs at the bottom surface and between two sets of solder balls, according to the IC designers.
U.S. Pat. No. 7,210,951 issued to Sinclair on May 1, 2007 discloses a top loaded burn-in socket for forming a plurality of electrical connections between a ball gird array (BGA) package having a plurality of conductive ball leads and an electrical component. The socket assembly includes a plurality of resilient electrical contacts; a cam being configured to position the contacts from a first position to a second position; a device guide plate including a plurality of openings for receiving the ball leads; and an actuating mechanism configured to interact with the cam to position the contacts, wherein an upper portion of the contacts engages the ball leads between the upper portion and an inclined surface of the device guide plate openings. Each ball is thus held in a manner that does not require the use of a hold down mechanism for effecting electrical continuity between the BGA package and the contacts of the subject burn-in socket.
However, it is noted that the one problem is likely to be caused when such an IC package like DDR is loaded in the above burn-in socket that the protrusions at the bottom surface of DDR interfere with the planar up surface 90 of the burn-in socket, and it will prevent the insertion of solder balls of the IC package into the plurality of holes formed in the planar up surface 90. Another problem is also exists in this conventional burn-in socket, that only one type of IC package could be loaded and tested. The guide plate has to be redesigned when a new IC package of different configuration is to be loaded, and therefore the cost is raised.